Two challenges we've run into here are isochronous media (audio, video) and multimedia presentation packages.
Audio and video are difficult for a couple of reasons. One problem is that they tend to be LARGE documents, which makes downloading tedious, yet the only way to get one out of DSpace is to download and then present. A suitably designed application *could* pull byte-range chunks out of the document and present them more quickly, but then there is the other problem: unlike text or drawings which just sit on the screen and can be delivered at any reasonable rate, audio and video evolve in time and must be presented at a constant (high) rate of delivery. One of the fundamental design decisions on which the Internet is based is that timing and even ordering of packet delivery are not critical. Both of these problems point to the use of a streaming service. Streaming clients expect to pull the material a bit at a time, and streaming protocols are designed to minimize timing problems. What we've tried is to deposit a SMIL wrapper as the DSpace bitstream and have that point to the actual presentation over on a streaming service. It works on some browsers, but SMIL is not yet as widely deployed as we might wish. One could do the same thing using e.g. RealMedia RAM pointer files, but that ties one down to a single vendor. We really ought to support open standards as they become available. Multimedia presentations take us to the next level of challenge, because they include a user interface program which lets the user control the delivery of the presentation. All the MM creator packages I've seen seem to assume that the result will be stamped on CDROMs and physically delivered. SMIL should eventually be the answer to this problem, since this is what it was really designed for: it's a language for defining buttons, projection areas, timing and synchronization for access to multiple streams of content. That's when the MM package makers get on board and leave their proprietary non-networkable baggage behind. We haven't come up with a satisfactory way to deal with such content until the dawning of that glorious day; our best response right now is to dump .iso images into the repo., and that's not at all what the user expects. DSpace can't do much about these problems, but the DSpace community can push the makers of producer and consumer software to build standards-based products. DSpace might be able to coordinate more closely with a streaming service by making it simple for that service to access bitstreams stored in DSpace. People who operate institutional streamers tend to see the content as ephemeral, which means that we wind up setting up our own streamer to ensure long-term availability. ++++++++++++++++++ There's one other problem I've noted with AV material: production values. We are often presented with horrors such as an AV recording made by pointing a camera at a projection screen while the presenter talks his way through a PowerPoint slideshow, and meetings that start with 10-15 minutes of unintelligible hubbub before the meeting comes to order. Technology can do nothing about this. We need to get the word out that people should think about preservation in advance and plan their capture of presentations. Simply editing down to something presentable will help in some cases, while in others the presentation would benefit from being designed over again with network delivery in mind (transcript+slides instead of chalk-talk recording, maybe packaged with SMIL to make a neat whole of it). This is really an extension of what we do in advising depositors about file formats that work well for long-term preservation. -- Mark H. Wood, Lead System Programmer [EMAIL PROTECTED] Typically when a software vendor says that a product is "intuitive" he means the exact opposite.
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